EP0337054A2 - Dispositif interférométrique - Google Patents

Dispositif interférométrique Download PDF

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Publication number
EP0337054A2
EP0337054A2 EP89100386A EP89100386A EP0337054A2 EP 0337054 A2 EP0337054 A2 EP 0337054A2 EP 89100386 A EP89100386 A EP 89100386A EP 89100386 A EP89100386 A EP 89100386A EP 0337054 A2 EP0337054 A2 EP 0337054A2
Authority
EP
European Patent Office
Prior art keywords
substance
filter
distance
interference
plate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89100386A
Other languages
German (de)
English (en)
Other versions
EP0337054A3 (fr
Inventor
Michael Zöchbauer
Walter Fabinski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Training Center GmbH and Co KG
Original Assignee
Hartmann and Braun AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hartmann and Braun AG filed Critical Hartmann and Braun AG
Publication of EP0337054A2 publication Critical patent/EP0337054A2/fr
Publication of EP0337054A3 publication Critical patent/EP0337054A3/fr
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/12—Generating the spectrum; Monochromators
    • G01J3/26—Generating the spectrum; Monochromators using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/067—Electro-optic, magneto-optic, acousto-optic elements

Definitions

  • the invention relates to an interferometric device for detecting a substance according to the preamble of claim 1.
  • a known interferometric device of this type is described in DE-OS 26 04 471.
  • an arrangement which comprises the following elements: a polarizer, a birefringent plate, the thickness of which is equal to the characteristic optical path difference of the substance sought, and a second polarizer, which functions as an analyzer.
  • This device requires constant rotation of the analyzer and is therefore subject to wear due to the necessary mechanical drive. This makes it difficult to use in applications that require long service lives and low maintenance, as is the case, for example, with measurements in industrial processes.
  • the invention has for its object to provide an interferometric device according to the preamble of claim 1, which makes it possible to detect molecules with a structured, in particular periodic or quasi-periodic absorption spectrum highly selectively and at the same time to completely dispense with mechanically moving parts.
  • An electrically tunable filter which consists of an electro-optically active material, is used as the interferometric element.
  • Both crystal plates e.g. made of lithium niobate, as well as optical cells filled with birefringent liquid crystals. Such materials change their refractive index z. B. depending on an applied electric field.
  • the electro-optical plate or the liquid crystal cell is partially transparent mirrored on both ends, so that a Fabry-Perot element is formed. The half-width of the Fabry-Perot element can be adjusted in a known manner via the degree of mirroring.
  • an embodiment should be chosen that covers a relatively large part of the absorption spectrum. This is particularly advantageous when there is a quasi-periodic line spectrum, as in the case of the CO molecule at 4.6 ⁇ m.
  • the thickness of the electro-optical plate or of the cell filled with liquid crystals is selected such that the interference pattern generated corresponds to the characteristic optical path difference of the molecule that is to be detected. This means that the distance between the individual interference orders of the electrically tunable filter corresponds exactly to the distance between the periodic absorption lines of the substance to be detected.
  • the interference pattern of the filter As a starting point, it is initially assumed that the interference pattern of the filter, as shown in FIG. 1b, is exactly matched with the periodic absorption lines of the substance, which are shown in FIG. 1a.
  • the device according to the invention is now in the measuring phase, which is characterized by the greatest possible absorption of the substance sought.
  • the interference pattern By applying an electric field to the partially transparent mirror surfaces of the electrically tunable filter, the interference pattern can now be shifted in a simple manner so that the interference pattern of the filter and the absorption lines of the substance are just "on gap"; Fig. 2 shows this state. In this state (reference phase) the absorption of the substance sought is zero.
  • Periodic modulation of the electrical field enables a constant change between the measuring and reference phases to be achieved without the need for mechanically moving parts. Compared to mechanical modulation, the electrical modulation according to the invention allows much higher modulation frequencies, which allows a better useful / interference signal ratio and faster measurement.
  • a high selectivity is achieved especially when a single line is generated with the interferometer according to the invention, such that its bandwidth is small compared to the distance between two lines in a periodic or quasi-periodic absorption spectrum.
  • a useful signal is always generated when the measurement component is present in the absorption path. Since the covered correlation area is smaller than in the variant described above, larger noise is to be expected here.
  • the advantage lies in the selectability of the wavelength. This can be placed in an area where there is no overlap with an interfering component.
  • a third possibility of using the device described here advantageously arises if the spectrum is not periodic but at least structured.
  • a useful signal is also generated in the presence of the same. If the wavelength is chosen so that the absorption of interfering components in this area is low or does not change or changes only slightly over the wavelength, the desired selectivity is generated with the arrangement according to the invention.
  • the broadband light coming from the radiation source L is initially limited by an optical filter F to the part of the radiation of interest.
  • the mirrors S have electrical connections that lead to a modulation unit M.
  • a lens O is arranged behind the filter E.
  • the interferometric evaluation area can be limited to a central area near the optical axis by means of an aperture B.
  • the radiation passing through the diaphragm is detected by the detector D and converted into an electrical signal.
  • a cell Z filled with birefringent liquids can also be used, as shown in FIG. 3b.
  • the translucent windows I of cell Z have a partially translucent mirrored layer S on the inside.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Biochemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Spectrometry And Color Measurement (AREA)
EP19890100386 1988-04-14 1989-01-11 Dispositif interférométrique Withdrawn EP0337054A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3812334 1988-04-14
DE3812334A DE3812334A1 (de) 1988-04-14 1988-04-14 Interferometrische einrichtung

Publications (2)

Publication Number Publication Date
EP0337054A2 true EP0337054A2 (fr) 1989-10-18
EP0337054A3 EP0337054A3 (fr) 1991-01-16

Family

ID=6351915

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890100386 Withdrawn EP0337054A3 (fr) 1988-04-14 1989-01-11 Dispositif interférométrique

Country Status (3)

Country Link
US (1) US4999013A (fr)
EP (1) EP0337054A3 (fr)
DE (1) DE3812334A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0396319A1 (fr) * 1989-05-01 1990-11-07 Rosemount Analytical Inc. Procédé et dispositif pour le mesurage des absorptions optiques de mélanges gazeux
EP0409765A3 (fr) * 1989-07-19 1991-03-27 Hartmann & Braun Aktiengesellschaft Appareil interférométrique
JPH0372239A (ja) * 1989-08-03 1991-03-27 Hartmann & Braun Ag 干渉測定分析装置
EP0753733A1 (fr) * 1995-07-07 1997-01-15 Vaisala Oy Méthode de contrÔle d'un interféromètre Perot-Fabry à étalon court utilisé dans un appareil de mesure infra-rouge non dispersif
FR2759167A1 (fr) * 1997-01-31 1998-08-07 Schlumberger Ind Sa Procede et dispositif de determination d'une concentration d'un volume de gaz

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991005988A1 (fr) * 1989-10-12 1991-05-02 Hartmann & Braun Aktiengesellschaft Procede et agencement pour la spectroscopie fabry-perot
US5225888A (en) * 1990-12-26 1993-07-06 International Business Machines Corporation Plasma constituent analysis by interferometric techniques
US5208651A (en) * 1991-07-16 1993-05-04 The Regents Of The University Of California Apparatus and method for measuring fluorescence intensities at a plurality of wavelengths and lifetimes
FI96450C (fi) * 1993-01-13 1996-06-25 Vaisala Oy Yksikanavainen kaasun pitoisuuden mittausmenetelmä ja -laitteisto
US5452121A (en) * 1993-11-12 1995-09-19 Northrop Grumman Corporation Variable spectral resolution agile filter
US6661950B1 (en) 2001-01-10 2003-12-09 Nomadics, Inc. Microresonator-based tuned optical filter
AU2007226476B2 (en) * 2006-03-16 2011-03-31 Basf Se Process for contacting two phases whose contact is accompanied by heat evolution
DE102012007030C5 (de) * 2012-04-05 2019-01-10 Drägerwerk AG & Co. KGaA Vorrichtung und Verfahren zur schnellen Aufnahme eines Absorptionsspektrums eines Fluids
US9976901B2 (en) * 2014-08-14 2018-05-22 Bae Systems Information And Electronic Systems Integration Inc. Ultra-narrow band-pass via etalon external to a long-wavelength infrared sensor
US20240044795A1 (en) * 2022-08-04 2024-02-08 Instrumentation Laboratory Co. Optical analyte sensor

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3939348A (en) * 1974-06-11 1976-02-17 Allied Chemical Corporation Infrared gas analysis
US3984190A (en) * 1974-11-26 1976-10-05 Allied Chemical Corporation Simultaneous transmission of periodic spectral components by plural interferometric means
FR2300998A2 (fr) * 1975-02-11 1976-09-10 Anvar Dispositif pour la spectrometrie interferentielle a modulation selective
US4595292A (en) * 1983-07-29 1986-06-17 The Perkin-Elmer Corporation Apparatus for detecting coherent radiation and unequal path interferometers
FR2566532B1 (fr) * 1984-06-22 1986-09-12 Elf France Detecteur de gaz par interferometrie
US4735506A (en) * 1985-04-01 1988-04-05 Litton Systems, Inc. Phase nulling optical gyroscope
FR2581190B1 (fr) * 1985-04-25 1987-06-19 Elf France Detecteur interferometrique de gaz
US4743114A (en) * 1986-07-11 1988-05-10 The Perkin-Elmer Corporation Fabry-Perot scanning and nutating imaging coherent radiometer
GB8621438D0 (en) * 1986-09-05 1986-10-15 Secr Defence Electro-optic device
DE3831576A1 (de) * 1988-09-16 1990-05-10 Maihak Ag Optisches strahlungsfilter

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0396319A1 (fr) * 1989-05-01 1990-11-07 Rosemount Analytical Inc. Procédé et dispositif pour le mesurage des absorptions optiques de mélanges gazeux
EP0409765A3 (fr) * 1989-07-19 1991-03-27 Hartmann & Braun Aktiengesellschaft Appareil interférométrique
JPH0372239A (ja) * 1989-08-03 1991-03-27 Hartmann & Braun Ag 干渉測定分析装置
EP0753733A1 (fr) * 1995-07-07 1997-01-15 Vaisala Oy Méthode de contrÔle d'un interféromètre Perot-Fabry à étalon court utilisé dans un appareil de mesure infra-rouge non dispersif
FR2759167A1 (fr) * 1997-01-31 1998-08-07 Schlumberger Ind Sa Procede et dispositif de determination d'une concentration d'un volume de gaz
EP0857964A1 (fr) * 1997-01-31 1998-08-12 Schlumberger Industries S.A. Procédé et dispositif de détermination d'une concentration d'un volume de gaz

Also Published As

Publication number Publication date
EP0337054A3 (fr) 1991-01-16
DE3812334A1 (de) 1989-10-26
US4999013A (en) 1991-03-12

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